The beta/nightly guys are doing it because it's their hobby. This is entertainment for them. Like the guys who just analyze the hell out of game graphics instead of actually playing the games. These guys are always complaining about how their stuff isn't working right, but they love it.
If using the OS as a tool to get things done is your main concern then you back off to what gets you the new features you need/want.
If you're a luddite and afraid of being kicked out of your habits then you never update until hardware death forces you, even though you're missing a lot of upgrades that could help you do things better and faster. Some of these guys admit it, which is fair enough (my Mom doesn't want to have to relearn), and the others have endless lame excuses.
I used to be one of the first guys, now I'm one of the middle guys. Debian testing dist-upgrade, Windows 8.1 with Metro stripped out, Android 5.1.1. It just works without being bleeding edge. Okay, Win10 on one non-critical machine, for my inner child.